单点登录实现（spring session+redis完成session共享）

一、前言

　　项目中用到的SSO，使用开源框架cas做的。简单的了解了一下cas，并学习了一下单点登录的原理，有兴趣的同学也可以学习一下，写个demo玩一玩。

二、工程结构

　　我模拟了 sso的客户端和sso的服务端， sso-core中主要是一些sso需要的过滤器和工具类，缓存和session共享的一些XML配置文件，还有springmvc需要的一下jar包的管理。sso-cache中配置了redis缓存策略。

三、单点登录原理图

　　简单描述：

　　用户访问系统1的受保护资源，系统1发现用户未登录，跳转至sso认证中心，并将自己的地址作为参数

　　sso认证中心发现用户未登录，将用户引导至登录页面

　　用户输入用户名密码提交登录申请

　　sso认证中心校验用户信息，创建用户与sso认证中心之间的会话，称为全局会话，同时创建授权令牌

　　sso认证中心带着令牌跳转会最初的请求地址（系统1）

　　系统1拿到令牌，去sso认证中心校验令牌是否有效

　　sso认证中心校验令牌，返回有效，注册系统1

　　系统1使用该令牌创建与用户的会话，称为局部会话，返回受保护资源

　　用户访问系统2的受保护资源

　　系统2发现用户未登录，跳转至sso认证中心，并将自己的地址作为参数

　　sso认证中心发现用户已登录，跳转回系统2的地址，并附上令牌

　　系统2拿到令牌，去sso认证中心校验令牌是否有效

　　sso认证中心校验令牌，返回有效，注册系统2

　　系统2使用该令牌创建与用户的局部会话，返回受保护资源

四、单点登录实现

　　1.SSOFilter.java（sso client filter实现）

import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import com.alibaba.fastjson.JSONObject;
import com.hjz.sso.utils.RestTemplateUtil;public class SSOFilter implements Filter{public static Logger logger = LoggerFactory.getLogger(SSOFilter.class);private String SSO_SERVER_URL;private String SSO_SERVER_VERIFY_URL;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {SSO_SERVER_URL = filterConfig.getInitParameter("SSO_SERVER_URL");SSO_SERVER_VERIFY_URL = filterConfig.getInitParameter("SSO_SERVER_VERIFY_URL");if(SSO_SERVER_URL == null) logger.error("SSO_SERVER_URL is null.");if(SSO_SERVER_VERIFY_URL == null) logger.error("SSO_SERVER_VERIFY_URL is null.");}@Overridepublic void doFilter(ServletRequest req, ServletResponse res,FilterChain chain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest) req;HttpServletResponse response = (HttpServletResponse) res;//请求中带有token，去sso-server验证token是否有效String authority = null;if(request.getParameter("token") != null) {boolean verifyResult = this.verify(request, SSO_SERVER_VERIFY_URL, request.getParameter("token"));if (verifyResult) {chain.doFilter(req, res);return;} else {authority = "token->" + request.getParameter("token") + " is invalidate.";}}HttpSession session = request.getSession();if (session.getAttribute("login") != null && (boolean)session.getAttribute("login") == true) {chain.doFilter(req, res);return;}//跳转至sso认证中心String callbackURL = request.getRequestURL().toString();StringBuilder url = new StringBuilder();url.append(SSO_SERVER_URL).append("?callbackURL=").append(callbackURL);if(authority != null) {url.append("&authority=").append(authority);}response.sendRedirect(url.toString());}private boolean verify(HttpServletRequest request, String verifyUrl, String token) {String result = RestTemplateUtil.get(request, verifyUrl + "?token=" + token, null);JSONObject ret = JSONObject.parseObject(result);if("success".equals(ret.getString("code"))) {return true;}logger.error(request.getRequestURL().toString() + " : " + ret.getString("msg"));return false;}@Overridepublic void destroy() {}}

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　　2.LoginController.java（sso server登录controller）

import java.util.UUID;import javax.servlet.http.HttpSession;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;@Controller
@RequestMapping("sso")
public class LoginController {private Logger logger = LoggerFactory.getLogger(LoginController.class);@RequestMapping(value="login", method={RequestMethod.GET, RequestMethod.POST})public String login(HttpSession session, Model model,@RequestParam(value="name", required=false) String name,@RequestParam(value="password", required=false) String password) {if(name == null && password == null) return "login";if("admin".equals(name) && "admin".equals(password)) {String token = UUID.randomUUID().toString();session.setAttribute("login", true);session.setAttribute("token", token);return "index";} else {model.addAttribute("error", true);model.addAttribute("message", "用户名或密码错误。");return "login";}}
}

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　　3.ValidateController.java（sso server验证token controller）

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;import com.alibaba.fastjson.JSONObject;@Controller
@RequestMapping("sso")
public class ValidateController {@RequestMapping("verify")@ResponseBodypublic JSONObject verify(HttpServletRequest request, @RequestParam String token) {HttpSession session = request.getSession();JSONObject result = new JSONObject();if(session.getAttribute("token") != null && token.equals(session.getAttribute("token"))) {result.put("code", "success");result.put("msg", "认证成功");} else {result.put("code", "failure");result.put("msg", "token已失效，请重新登录！");}return result;}}

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　　4.在sso client工程中加上SSOFilter（web.xml部分配置）

<filter><filter-name>ssoFilter</filter-name><filter-class>com.hjz.sso.filter.SSOFilter</filter-class><init-param><param-name>SSO_SERVER_URL</param-name><param-value>http://localhost:8088/sso-server/sso/login</param-value></init-param><init-param><param-name>SSO_SERVER_VERIFY_URL</param-name><param-value>http://localhost:8088/sso-server/sso/verify</param-value></init-param>
</filter><filter-mapping><filter-name>ssoFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>

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　　基本模型已经出来了，启动sso-client 和 sso-server（本人都部署到了同一个tomcat下），试图去验证单点登录。测试的时候，从浏览器中的cookie中查看，可以看到 localhost域下有多个JSESSIONID。这也难怪， Tomcat中的每一个application都会创建自己的session会话。那接下来的事情就是解决 session 共享的问题，这样我们就可以完成我们的单点登陆了。

　　为完成 session共享，这里推荐两种方案。一个是 tomcat+redis实现session共享，一个是 spring session+redis实现session共享。我这里采用了第二种方案，详情请接着看下面的步骤。

　　5.为每个工程的web.xml中增加spring session代理filter的配置

<!-- session 代理 -->
<filter><filter-name>springSessionRepositoryFilter</filter-name><filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter><filter-mapping><filter-name>springSessionRepositoryFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>

　　6.在sso-core中加入缓存和spring session的xml配置（cache-config.xml）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"default-lazy-init="false"><description>Cache公共配置</description><bean id="cookieSerializer" class="org.springframework.session.web.http.DefaultCookieSerializer"><property name="cookiePath" value="/"></property></bean><bean class="com.sso.cache.config.CacheConfig"/><bean class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration"><property name="maxInactiveIntervalInSeconds" value="1800"></property></bean>
</beans>

　　这里说一下为什么有定义一个 cookieSerializer 这个bean。参看RedisHttpSessionConfiguration的源码，发现它继承了SpringHttpSessionConfiguration，继续查看源码，发现SpringHttpSessionConfiguration中实现了我们配置的spring session代理filter，如下所示。

SpringHttpSessionConfiguration.java

@Bean
public <S extends ExpiringSession> SessionRepositoryFilter<? extends ExpiringSession> springSessionRepositoryFilter(SessionRepository<S> sessionRepository) {SessionRepositoryFilter sessionRepositoryFilter = new SessionRepositoryFilter(sessionRepository);sessionRepositoryFilter.setServletContext(this.servletContext);if (this.httpSessionStrategy instanceof MultiHttpSessionStrategy) {sessionRepositoryFilter.setHttpSessionStrategy((MultiHttpSessionStrategy) this.httpSessionStrategy);} else {sessionRepositoryFilter.setHttpSessionStrategy(this.httpSessionStrategy);}return sessionRepositoryFilter;
}

　　查看源码，可以发现 SpringHttpSessionConfiguration使用的默认会话策略（httpSessionStrategy）是CookieHttpSessionStrategy。继续查看CookieHttpSessionStrategy的源码，如新建session写入cookie。

public void onNewSession(Session session, HttpServletRequest request, HttpServletResponse response) {Set sessionIdsWritten = getSessionIdsWritten(request);if (sessionIdsWritten.contains(session.getId())) {return;}sessionIdsWritten.add(session.getId());Map sessionIds = getSessionIds(request);String sessionAlias = getCurrentSessionAlias(request);sessionIds.put(sessionAlias, session.getId());String cookieValue = createSessionCookieValue(sessionIds);this.cookieSerializer.writeCookieValue(new CookieSerializer.CookieValue(request, response, cookieValue));
}

　　cookieSerializer 默认是 DefaultCookieSerializer。查看DefaultCookieSerializer 的 writeCookieValue方法如下。

public void writeCookieValue(CookieSerializer.CookieValue cookieValue) {HttpServletRequest request = cookieValue.getRequest();HttpServletResponse response = cookieValue.getResponse();String requestedCookieValue = cookieValue.getCookieValue();String actualCookieValue = requestedCookieValue + this.jvmRoute;Cookie sessionCookie = new Cookie(this.cookieName, actualCookieValue);sessionCookie.setSecure(isSecureCookie(request)); sessionCookie.setPath(getCookiePath(request));String domainName = getDomainName(request);if (domainName != null) {sessionCookie.setDomain(domainName);}if (this.useHttpOnlyCookie) {sessionCookie.setHttpOnly(true);}if ("".equals(requestedCookieValue)) {sessionCookie.setMaxAge(0);} else {sessionCookie.setMaxAge(this.cookieMaxAge);}response.addCookie(sessionCookie);
}

　　sessionCookie.setPath(getCookiePath(request));这块有一个问题，看一下getCookiePath方法的实现，如下。

private String getCookiePath(HttpServletRequest request) {if (this.cookiePath == null) {return request.getContextPath() + "/";}return this.cookiePath;
}

　　如果要实现单点登录，就不要使用默认的 cookiePath 的值。所以，我定义了一个 cookieSerializer 的bean，并指定了 cookiePath 的值。 SpringHttpSessionConfiguration中如下方法可以自动装配我们配置的cookieSerializer，而不是使用默认的。

@Autowired(required = false)
public void setCookieSerializer(CookieSerializer cookieSerializer) {this.defaultHttpSessionStrategy.setCookieSerializer(cookieSerializer);
}

　　7.在每个工程中的spring公共配置文件中增加如下配置。

<import resource="classpath*:cache-config.xml"/>

　　8.后端之间rest请求传递 session ID。

private static ResponseEntity<String> request(ServletRequest req, String url, HttpMethod method, Map<String, ?> params) {HttpServletRequest request = (HttpServletRequest) req;//获取header信息HttpHeaders requestHeaders = new HttpHeaders();Enumeration<String> headerNames = request.getHeaderNames();while (headerNames.hasMoreElements()) {String key = (String) headerNames.nextElement();String value = request.getHeader(key);requestHeaders.add(key, value);}HttpEntity<String> requestEntity = new HttpEntity<String>(params != null ? JSONObject.toJSONString(params) : null, requestHeaders);ResponseEntity<String> rss = restTemplate.exchange(url, method, requestEntity, String.class);return rss;
}